3Com WX3000 operation manual 1Format of Garp packets, Field Description Value

Figure 1-1Format of GARP packets

DA

DA

length

DSAP

SSAP

Ctrl

PDU

Ethernet Frame

1	3								N
Protocol ID		Message 1		...			Message N	End Mark
1		2			N
Attribute Type		Attribute List
1							N
Attribute 1	...		Attribute N		End Mark
1		2			3			N
Attribute Length		Attribute Event				Attribute Vlaue

GARP PDU structure

Message structure

Attribute List structure

Attribute structure

The following table describes the fields of a GARP packet.

Table 1-1Description of GARP packet fields

Field		Description		Value
Protocol ID	Protocol ID		1
Message		Each message consists of two parts:		—
		Attribute Type and Attribute List.
Attribute Type		Defined by the specific GARP		The attribute type of GVRP is 0x01.
		application
Attribute List		It contains multiple attributes.	—
		Each general attribute consists of
		three parts: Attribute Length,
Attribute		Attribute Event, and Attribute Value.		—
		Each LeaveAll attribute consists of
		two parts: Attribute Length and
		LeaveAll Event.
Attribute Length		The length of the attribute		2 to 255 (in bytes)
				0: LeaveAll Event
				1: JoinEmpty
Attribute Event		The event described by the attribute		2: JoinIn
				3: LeaveEmpty
				4: LeaveIn
				5: Empty
				For GVRP packets, the value of this
Attribute Value		The value of the attribute		field is the VLAN ID; however, for
				LeaveAll messages, this field is invalid.
End Mark	End mark of an GARP PDU		The value of this field is fixed to 0x00.

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